The paper “Simultaneous Variable Selection” by Turlach, Venables, and Wright, published in Technometrics, August 2005, Vol. 47, No. 3 (U.S.A.) (hereinafter “Reference 1”), describes a “group lasso” method that can be used in the present invention. Numerical Optimization by Nocedal and Wright (2d ed. 2006), published by Springer Science+Business Media, LLC, describes, at Chapters 1, 5-7, 11, 12, and 17-19, methods that can be used in the present invention (hereinafter “Reference 2”).
The present inventive method is somewhat similar to non-rigid registration methods (commonly used in medical imaging) that register two images against each other; however, the present method takes no reference image. It registers the image against itself to find a smooth output image that is similar to the input image. No known prior art geometrically unbends an image in this way without having a reference image to compare to.